In most cases, healthcare providers will make a flu diagnosis on the basis of whether the disease is epidemic in the community and whether the person's complaints fit the current pattern of flu symptoms
. Healthcare providers rarely use laboratory tests to identify the virus and make a flu diagnosis during an epidemic. However, health officials do monitor certain U.S. health clinics and perform laboratory tests to determine which type of flu virus
is responsible for an epidemic.
(Click Flu for more information about the flu and its symptoms.)